Posted by
Guy, K2AV on
Nov 19, 2010; 10:14pm
URL: http://elecraft.85.s1.nabble.com/K3-Wide-AGC-threshold-tp5755595p5756793.html
There was some writeup I seem to remember that there were some
conditions where the lower threshold worked better. If one does NOT
PREFER using wide bandwidth to tune CW, the current stock setting IS
better for some reason that I can't give you.
My CW contesting use makes wide filters simply useless for CW. There
is ALWAYS a 35 over S9 signal up 350 Hz from me, no doubt due to some
natural law related to entropy. To get him out of my bandpass and
copy the calling S minus 3 QRP basement noodle antenna station that
accidentally disconnected his noodle and doesn't need it yet, I need
BOTH the DSP and the narrow filter. Your current filter situation
would be simply hopeless. You will love it when you finally get it.
73, Guy.
On Fri, Nov 19, 2010 at 4:50 PM, Bill W4ZV <
[hidden email]> wrote:
>
>
> Bob Henderson-2 wrote:
>>
>> The hardware AGC appears to be set at a level which precludes effective
>> utilisation of the 100dB+ DR of the DSP system.
>>
>
> Hi Bob...spoken like a former Orion user! You're absolutely correct...but
> it's actually much better than it was originally. Why? I have no clue.
>
> 73, Bill
>
> Hardware AGC threshold change (HAGC Mod Kit)
>
>
http://www.elecraft.com/K3/k3_app_notes.htm (scroll nearly to the bottom)
>
> SMD HAGCMDKT instructions
>
> Both through hole and SMD parts are included. Users can install either set
> of parts.
>
> Some users prefer tuning the band with a wide filter bandwidth selected
> (for example, using a 2.7 or 2.8 kHz SSB filter in CW mode rather than a 500
> Hz or narrower filter). Strong off-frequency signals (above about S9+5) that
> are inside the crystal filter passband can then activate the hardware AGC
> circuit, reducing the level of desired signals.
>
> This modification raises the hardware AGC threshold from about S9+5 to about
> S9+25 to +30. The new threshold still protects the DSP's analog-to-digital
> converter, while providing better receive performance when wider crystal
> filters are used. This is not as significant an issue when using narrow CW
> filters (500 Hz and below).
>
> --
> View this message in context:
http://elecraft.365791.n2.nabble.com/K3-Wide-AGC-threshold-tp5755595p5756731.html> Sent from the Elecraft mailing list archive at Nabble.com.
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